Endophyte-mediated regulatory effects and molecular mechanisms of understory cultivation mode on the metabolism of Panax quinquefolius L.

Abstract

Elucidating the regulatory mechanisms underlying the effects of understory cultivation on quality characteristics in Panax quinquefolius L. is essential for establishing an ecological cultivation mode. In this study, P. quinquefolius cultivated under understory and field conditions was used; Untargeted metabolomics was adopted to detect variations in metabolites; TMT-based quantitative proteomics was applied to analyze differences in protein expression profiles; 16S rRNA and ITS sequencing was conducted to characterize the composition and diversity of endophytic microbial communities. Results demonstrated that understory cultivation significantly enriched ginsenoside Rb1 and phenolic secondary metabolites such as epigallocatechin gallate and 4-methylcatechol. Concurrently, it upregulated the expression of ferulate 5-hydroxylase (F5H), a key protein in the phenylpropanoid biosynthesis pathway. F5H showed a significant positive correlation with epigallocatechin gallate and 4-methylcatechol. Understory cultivation also markedly altered the β-diversity of endophytic bacteria and the Shannon and Simpson indices of endophytic fungi, leading to the enrichment of beneficial genera such as Sphingomonas and Luteibacter . Microbial co-occurrence network analysis confirmed enhanced network stability under this cultivation mode. Luteibacter was significantly positively correlated with ginsenoside Rb1, 4-methylcatechol, and F5H. In conclusion, the understory cultivation mode is an effective approach to improving the quality of P. quinquefolius. This study, from an endophytic microecological perspective, reveals the molecular mechanisms by which understory cultivation enhances the accumulation of secondary metabolites and improves the quality of P. quinquefolius , providing a theoretical basis for optimizing its ecological cultivation technology and steadily improving medicinal material quality.